Csilla Farkas

Seniorforsker

(+47) 948 14 727
csilla.farkas@nibio.no

Sted
Ås - Bygg F20

Besøksadresse
Fredrik A. Dahls vei 20, 1430 Ås

Biografi

 Csilla Farkas holds an MsC in Surface hydrology (Russian State Hydrometeorological Universtity, St. Petersburg, Russia 1991) and a PhD in Earth Sciences (Eötvös Loránd University, Budapest, Hungary, 2002). She has worked in the fields of soil science, soil physics, soil hydrology, soilr erosion, catchment hydrology and water quality. 

She has experience i) in mathematical modelling of land use, management and climage change indicated changes in water, particle and nutrient transport in the soil and within the landscape and ii) in studying the spatio-temporal variability of soil properties and water balance elements. 

 

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The saturated hydraulic conductivity of soil, Ks, is a critical parameter in hydrological models that remains notoriously difficult to predict. In this study, we test the capability of a model based on percolation theory and critical path analysis to estimate Ks measured on 95 undisturbed soil cores collected from contrasting soil types. One parameter (the pore geometry factor) was derived by model fitting, while the remaining two parameters (the critical pore diameter, dc, and the effective porosity) were derived from X‐ray computed tomography measurements. The model gave a highly significant fit to the Ks measurements (p < 0.0001) although only ~47% of the variation was explained and the fitted pore geometry factor was approximately 1 to 2 orders of magnitude larger than various theoretical values obtained for idealized porous media and pore network models. Apart from assumptions in the model that might not hold in reality, this could also be attributed to experimental error induced by, for example, air entrapment and changes in the soil pore structure occurring during sample presaturation and the measurement of Ks. Variation in the critical pore diameter, dc, was the dominant source of variation in Ks, which suggests that dc is a suitable length scale for predicting soil permeability. Thus, from the point of view of pedotransfer functions, it could be worthwhile to direct future research toward exploring the correlations of dc with basic soil properties and site attributes.

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Climate change is expected to have a vigorous impact on soils and ecosystems due to elevated temperature and changes in precipitation (amount and frequency), thereby altering biogeochemical and hydrological cycles. Several phenomena associated with climate change and anthropogenic activity affect soils indirectly via ecosystem functioning (such as higher atmospheric CO2 concentration and N deposition). Continuous interactions between climate and soils determine the transformation and transport processes. Long-term gradual changes in abiotic environmental factors alter naturally occurring soil forming processes by modifying the soil water regime, mineral composition evolution, and the rate of organic matter formation and degradation. The resulting physical and chemical soil properties play a fundamental role in the productivity and environmental quality of cultivated land, so it is crucial to evaluate the potential outcomes of climate change and soil interactions. This paper attempts to review the underlying long-term processes influenced by different aspects of climate change. When considering major soil forming factors (climate, parent material, living organisms, topography), especially climate, we put special attention to soil physical properties (soil structure and texture, and consequential changes in soil hydrothermal regime), soil chemical properties (e.g. cation exchange capacity, soil organic matter content as influenced by changes in environmental conditions) and soil degradation as a result of longterm soil physicochemical transformations. The temperate region, specifically the Carpathian Basin as a heterogeneous territory consisting of different climatic and soil zones from continental to mountainous, is used as an example to present potential changes and to assess the effect of climate change on soils. The altered physicochemical and biological properties of soils require accentuated scientific attention, particularly with respect to significant feedback processes to climate and soil services such as food security.

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The determination of environmentally minimum water level in lakes is essential for the protection of their ecosystems. The assessment of minimum water level depends on a number of biotic and abiotic factors of the lake ecosystem; however, in many cases these factors are not easy to collect and assess in their entirety. At the same time, the lakes in many cases consist an important water reserve to meet the requirements arising from economic activities, e.g. industry, agriculture. In this paper, the morphological features in four lakes – Vegoritida, Petron, Cheimaditida and Zazari – of Northern Greece are analysed in order to assess their environmentally minimum water level. The morphological analysis is based on the relationship of the lake surface area and volume with the water level. An optimization method is applied taking into account that the biodiversity is favoured as the surface area covered by the lake is increased and the human water requirements are satisfied to the greatest possible extent by the available water volume of the lake. The environmentally minimum water level determined by the morphological analysis in the four lakes is compared with the minimum water level based on the analysis of the requirements of fish fauna and macrophytes.

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Catchment scale hydrological models are promising tools for simulating the effect of catchment-specific processes and management on soil and water resources. Here, we present a model intercomparison study of runoff simulations using three different semi-distributed rainfall-runoff catchment models. The objective of this study was to demonstrate the applicability of the Hydrologiska Byrans Vattenavdelning (HBV-Light); Precipitation, Evapotranspiration and Runoff Simulator for Solute Transport (PERSiST); and INtegrated CAtchment (INCA) models on Somogybabod Catchment, near Lake Balaton, Hungary. The models were calibrated and validated against observed discharge data at the outlet of the catchment for the period of January 1, 2006 –July 12, 2015. Model performance was evaluated using graphical representations, e.g. daily and monthly hydrographs and Flow Duration Curves (FDC) and model evaluation statistic; Nash–Sutcliffe efficiency (NSE) and coefficient of determination (R2). The simulation results showed that the models provided good estimates of monthly average discharge (0.60–0.90 NSE; 0.60–0.91 R2) and satisfactory results for daily discharge (0.46–0.62 NSE; 0.50–0.67 R2). We found that the application of hydrological models serves as a powerful basis for ensemble modelling of average runoff and could enhance our understanding of the eco-hydrological and transport processes within catchments. On the other hand, it can highlight the uncertainty of model forecasts and the importance of goal specific evaluation.

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A talajok tulajdonságainak javítása céljából végzett bioszénnel történő kezelések hatása a különböző fizikai, kémiai és biológiai tulajdonságú talajok esetében még nem teljesen ismert. Kísérleteinket homoktalajon végeztük az MTA ATK TAKI Őrbottyánban lévő kísérleti telepén, ahol kukoricát vetettek. Hét kezelést vizsgáltunk, négy ismétlésben. Három esetben a talaj különböző dózisban bioszenet és konstans dózisú műtrágyát tartalmazott (0,1 m/m%; 0,5 m/m%; 1 m/m%; jelölésük BC0,1M; BC0,5M; BC1,0M), három esetben pedig a fent említett bioszén dózisokat egységesen 10 t/ha komposzttal egészítettük ki (BC0,1K; BC0,5K; BC1,0K). Ezek mellett pedig kialakítottunk egy bioszén és komposzt mentes abszolút kontroll (K) kezelést is. Kutatásunk során talajszondákkal monitoroztuk a talajnedvességtartalmának alakulását, valamint statikus kamrás mintavételi eljárással a talajlégzést is mértük a kezelésekben. A talajnedvesség éves átlagát nézve 1% bioszénnel és komposzttal kezelt parcella esetében a talaj nedvességtartalma nem szignifikáns mértékben növekedett a bioszén és komposzt mentes abszolút kontroll környezethez képest. Csapadékesemények alkalmával az 1% bioszenet és komposztot tartalmazó parcellában nőtt meg legjobban a talajnedvesség, illetve hasonlóan alakult a nedvességtartalom a 0,5% bioszénnel kezelt műtrágyás parcellában is. Csapadékesemények után az összes bioszenet és műtrágyát, illetve bioszenet és komposztot tartalmazó parcellában gyorsabban száradt ki a talaj a kontrollhoz képest. A csapadékban szegényebb, szárazabb időszak alkalmával egyedül az 1% bioszenet és komposztot tartalmazó kezelés talajnedvessége volt magasabb a kontrollhoz képest, a 0,5% bioszénnel és műtrágyával kezelt, komposzt mentes esetben a nedvesség hasonlóan alakult a kontrollhoz viszonyítva, az összes többi esetben jóval az alatt maradtak az értékek. Összességében megállapítható, hogy a komposztot tartalmazó talajok érzékenyebben reagáltak a csapadékra, a legjobb vízgazdálkodást az 1% bioszén és komposzt kezelés esetében értük el. Önmagában a bioszén nagy mennyiségű (1,0 m/m%) adagolása nem volt egyértelműen talajnedvesség-növelő hatású. A bioszén szén-dioxid forgalomra történő hatását a talajlégzés mérésével vizsgáltuk. A bioszénnel, valamint műtrágyával kezelt és a kontroll kezelések között csak néhány esetben volt különbség. A komposzttal kevert bioszén kezelések alkalmával hasonló eredményre jutottunk, mint a műtrágyával kevert bioszén esetében. Eredményeink alapján arra következtethetünk, hogy a talajlégzés nem függött a bioszén dózisától. A bioszén talajlégzésre gyakorolt hatása közvetett módon, a talajnedvesség befolyásolásán keresztül valósul meg, mivel bioszenet alkalmazva bizonyos esetekben a talajnedvesség emelkedett a kontrollhoz képest, ekkor a talajlégzés ugyancsak magasabb lett, amely jelenség a komposzttal kezelt esetekben jól megfigyelhető volt.

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The main environmental stressor of the Baltic Sea is elevated riverine nutrient loads, mainly originating from diffuse agricultural sources. Agricultural practices, intensities, and nutrient losses vary across the Baltic Sea drainage basin (1.75 × 106 km2 , 14 countries and 85 million inhabitants). Six “Soil and Water Assessment Tool” (SWAT) models were set up for catchments representing the major agricultural systems, and covering the different climate gradients in the Baltic Sea drainage basin. Four fertilizer application scenarios were run for each catchment to evaluate the sensitivity of changed fertilizer applications. Increasing sensitivity was found for catchments with an increasing proportion of agricultural land use and increased amounts of applied fertilizers. A change in chemical fertilizer use of ±20% was found to affect watershed NO3-N loads between zero effect and ±13%, while a change in manure application of ±20% affected watershed NO3-N loads between zero effect and −6% to +7%.

Sammendrag

Knowledge of hydrological processes and water balance elements are important for climate adaptive water management as well as for introducing mitigation measures aiming to improve surface water quality. Mathematical models have the potential to estimate changes in hydrological processes under changing climatic or land use conditions. These models, indeed, need careful calibration and testing before being applied in decision making. The aim of this study was to compare the capability of five different hydrological models to predict the runoff and the soil water balance elements of a small catchment in Norway. The models were harmonised and calibrated against the same data set. In overall, a good agreement between the measured and simulated runoff was obtained for the different models when integrating the results over a week or longer periods. Model simulations indicate that forest appears to be very important for the water balance in the catchment, and that there is a lack of information on land use specific water balance elements. We concluded that joint application of hydrological models serves as a good background for ensemble modelling of water transport processes within a catchment and can highlight the uncertainty of models forecast.

Sammendrag

We overview the main goals and results of ongoing research on carbon cycle of agricultural lands in Hungary. This multi-scale and multi-objective research aims at a better understanding of CO2 exchange between agricultural ecosystems and the atmosphere. The integration of field measurements, laboratory measurements and remote sensing makes it possible to distinguish between and to evaluate the importance of different biotic and abiotic drivers of CO2 exchange on multiple spatial and temporal scales. Spatially representative data based on remote sensing provides invaluable information to constrain regional scale estimations of carbon balance of agricultural lands. The main three pillars of carbon cycle research in our case are field and laboratory measurements of soil respiration, field measurements of ecosystem CO2 fluxes (using the eddy-covariance method), and remote sensing based modelling of carbon cycle components. Measurement sites include various agricultural fields: crop rotation, peach plantation, croplands of a mixed agricultural landscape. Heterogeneous agricultural vegetation is a typical land cover type that occupies major parts ofHungary.

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Soil biological properties and CO 2 emission were compared in undisturbed grass and regularly disked rows of a peach plantation. Higher nutrient content and biological activity were found in the undisturbed, grass-covered rows. Significantly higher CO 2 fluxes were measured in this treatment at almost all the measurement times, in all the soil water content ranges, except the one in which the volumetric soil water content was higher than 45%. The obtained results indicated that in addition to the favourable effect of soil tillage on soil aeration, regular soil disturbance reduces soil microbial activity and soil CO 2 emission

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The Hungarian Detailed Soil Hydrophysical Database, called MARTHA ver2.0 has been developed to collect information on measured soil hydraulic and physical characteristics in Hungary. Recently this is the largest detailed national hydrophysical database, containing controlled information from a total of 15,005 soil horizons. Two commonly used pedotransfer functions were tested to evaluate the accuracy of the predictions on the MARTHA data set, representative for Hungarian soils. In general, the application of both examined pedotransfer functions (Rajkai, 1988; Wösten et al., 1999) was not very successful, because these PTFs are representative for other soil groups. The classification tree method was used to evaluate the effect of soil structure on the goodness of estimations. It was found that using the soil structure data the inaccuracies of soil water retention predictions are more explainable and the structure may serve as a grouping variable for the development of class PTFs.

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An overview of carbon dioxide (CO2) exchange and soil respiration measurements is given for representative Hungarian agroecosystems. We present results of long term atmosphere/biosphere CO2 exchange measurements carried out at the Hungarian tall tower site (Hegyhátsál). Tall tower net ecosystem exchange (NEE) measurements provided consistent estimates of landscape-wide carbon dioxide dynamics. During the period of 1997-2008 the region mostly behaved as a net CO2 sink on annual scale. Year-round NEE was in the range of  352±49 g C m 2 year-1 and 43±9 g C m-2 year-1 (negative values indicate uptake). The measurements are representative to a mixture of arable lands with small contribution from other biome types. Effects of different soil tillage methods - applied in two long term tillage experiments (Józsefmajor, Karcag) and in a peach orchard (Vác) - on soil CO2 emission are also introduced. Soil respiration rate highly depended on the depth of soil disturbance and on the date of the measurements; CO2 emissions measured immediately after tillage applications and during the vegetation period showed contradictory tendencies. Results obtained from a newly developed laboratory CO2 emission measurement method indicated strong coherences between soil carbon dioxide fluxes and soil water potential values.

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Measurement of biosphere-atmosphere exchange of various greenhouse gases requires different techniques. In case of carbon dioxide the net ecosystem exchange (NEE) is usually measured by the eddy covariance method. In the lack of these measurements in forests the carbon dioxide uptake can be estimated by detecting changes in sequestrated carbon stocks or by using tree growth (dendrometric) measurements. The soil CO2, CH4 and N2O efflux/exchange rates can be determined using in situ chamber techniques, or laboratory incubation measurements. Static and dynamic, manual and automatic chamber methods, as well as photo acoustic, gas chromatography and infrared detections can be used for this purpose. This chapter gives a general overview of the approaches applied in studies presented in this book for evaluating the greenhouse gas exchange between the biosphere and atmosphere.

Sammendrag

The latest climate change scenarios, forecasting for the Tisza watershed valuable increase in the occurrence of extreme weather events as well as changes in land use policy increased the demand on knowledge towards sustainable flood plain and water reservoir management. The main objective of the present study was to develop an appropriate methodology that could be used for describing the soil water regime of the Bodrog Interfluve floodplain area at sub-regional scale and to derive the corresponding soil and hydrological database. This paper describes the fine-scale spatial soil database, constructed for characterizing the soil cover of the Hungarian territory of the Bodrog Region; the monitoring system, established in the study area and the mathematical modeling procedure carried out for better description of soil water regime and water balance elements. Further, performance and results of a scenario analyses are presented for evaluating the possible effects of two recently predicted climate change scenarios on soil water regime of a sensitive floodplain area. It was concluded, that based on the adaptation of a water balance simulation model and on the spatial soil physical database, the water regime of the dominant natural, semi-natural and agrarian ecosystems could be estimated. Compared to the present circumstances, the results of the scenarios analyses indicated more uneven and extreme surface and subsurface hydrological situations under changing climatic conditions.